Screen web tensioner



F. J. PROKOP ET AL Dec. 7, 1954 SCREEN WEB TENSIONER 2 Sheecs-Sheet 2 Fi1ed Ost. 13. 1953 v INVENTORS: FRANK J. PROKOP RSHALL M. PELLAR 'BY= ZMQWm-urf ATT'YS United States Patefit This invention relates; to: screens of. thegenerab type on=.whichpicturesr are projeeted and:has particular reference-to means for-tensioning a screen web:-

The. mainzobjects rof thiswinvemtion:are- (o: provide: an improv.eclnwebfi tensioning .mechanisnm for p icture screens whi clnwillxassure: thatthe web iof 1the screencanbe stretchedtar1trii1 an saccurate planan disposition;= and to provide tensioning: meehanism which suppl'ement the pull 0f. xthe usual: curtaim rollervtensioning devices; being normally ain'active .but .adapted for subje'cting the screen web tmaddit-ional .strain =bymanual= means so=-as to pull?the web in such manner: asto remove any=tend'ency=0f *the same to. curl, KQI: warp;v or otherwise de'part from-exact conformity withi0ne plane.

A- specific rembodiment of= this invention= i's= shownin th'eaecompanying drawings in which:

Fig'ure 1 is; a .perspectivei'view of a picture*sereen of thefltype- :to. which .this invention particularl-Y -relatesv Fig.: 2 318 anenlarged perspective -view illstrating the mounting elements of the screen when thte=webisstretched taut.

Fig. 3 isa.fragmentary-perspective view of-one end of the screen housing;:

Fig. 4 is an exploded perspective view of the same illustrating the form of and assembl'ysequence of the:p artsof the tensio nirig device aecording4othe -=present: invention.

bearingspider of the curt-aihmollrand other parts ofthe 'tensioning mechanisrn removed; 1

y of the tensioning meehanism in their locked position.

In the form shown in the drawings, the screen comprises an upright standard 10 mounted on tripod legs 11 and having an extension rod 12 at the upper end cf which isa hanger hook 13. The screen web 14 has a bail 15 mounted atthe midpoint of a resilient spreader bar 16 which serves as a suspension spring and is attached at its ends to the stiff slat 17 at the upper or free end of the screen web 14. The lower end of the screen web is attached to a curtain roller 18 equipped with the usual internal torsion spring 19 of sufficient winding capacity to roll up the entire length of the web 14.

In the form shown, the roller 18 is housed in a cylindrical casing 20 which is mounted at its midpoint on the front side of the standard 10. The casing 20 has a longitudinal slot 22 through which the web 14 is withdrawn.

The roller 18 has journal bearings at both' ends including the usual shaft 23 at the so-called live end of the roller 18 where the helical torsion spring 19 is located and also has a shaft 24 at the so-called dead end cf the spring roller which is at the right of the detail shown in Figs. 3 to 7 inclusive. The shaft 24 is integrally secured centrally on the disc 25 which in turn is attached to the end of the dead end of the roller 18. The shaft 24 is square in cross section or otherwise shaped locally for relatively non-rotative but axial sliding engagement with the crank arm 26.

The end of the casing 20 adjacent the dead end of the roller 18 has mounted thereon a stationary cap 27 which serves as a spider for supporting the bearing 28 in which the shaft 24 rotates. This cap has an annular series of perforations 29 which provide shoulders 30 2,696249 Fatented. Dec. 7, 1954- ard. andvallow the: spring 19 to maintaim the webl4 stretched. tautunder the:normal spring acti0n.z

A flanged disc.33,zfixedr:at the outer endofiihe shaft 24, serves.=as.a knobzxfer manualwrotation of the= roller 18 and; also." as an ornarnental. covering:cap= forthe adjacent end of. the.casing=and.-.therlatch mechanism; This cap 33.is attached to the.shaft 24bymeans ofa set screw 34 andlock washer 35.:

Thecap::33. also has an aperture 36: through: which a lug.-37 011 the cranln arm 26 extends loosely,' so as to ser;ve as a button wherreby the operator maypush the latch. tongue 31 ;into-. engagement with one of the shoulders .30 of the. keeper-apertures 29; in which position it lS==ShOW11HF1g 7. Thisviewshows the relation ofthe latoh::members aften the web 1'4 has been withdrawn from the. casing20;:its bail15has been hung-on the hook 13:and.:the pnll on= thewebby=the spring l9 hambeen supplernented%zby manual rotation of the cap: 33. agairist the.pull of the suspensiom spring 163 There is thusproducedisufiieiemt 1ension onthe web *to cause friction be tween thekeeper shoulder andthe latch tongne31 to hold the-roller. 18zlocked despitethe pressure of thecompression spring 32 tending to releaseit-L; When-the tensionof the.suspension: spring isreleasecl bYrel'easing the extension rodandqallbwing it totelescope -within the standard 10=!invthe usual Imanner; ths fric'ti0n is reduced- -and= the spring 32fireleases the hold of the leiteh.

The operation of th'e device shown isas followsx- After the screen has been spread up0n;the-hanger=in the positi0n=imwhich it isshownin Fig. l, it=is under the n01mal tensionstrain producedbj/ the rollersp ring 19. But in orderto: stretchit so that its front-picture projection reeeivin'g-f-ziee is absolutely flat, additional stretchin'gstrain upon the web*l4 may be=applieduniformlY= threughout its wid-th by manual rotation of t-h'e knob 33 in the same direction in which the roller 18 is normally urged by the spring 19.

When the web 14 is thus satisfactorily stretched to exact planar form, the Operator pushes the button 37 inward so as to project the latch tongue 31 into the nearest one of the apertnres 29. The pressure thus eaused now produces suflicient friction between the shoulder 30 and the latch tongue 31 to prevent the arm 26 from being shifted by the pressure of the spring 32.

The resilient spreader bar 16 of the bail 15 assures that the strain of the web 14 is equally resisted at all points throughout the length of the slat 17. This strain pulls the spreader bar 16 to slightly bowed position as shown in Fig. 2, when the web 14 is subject to the additional strain produced by manual rotation cf the knob 33 for applying extra strain upon the web.

The instant that the extension rod 12 is telescoped in the standard 10, the strain produced by the manual setting of the latch mechanism reduces the friction between the latch tongue 31 and the shoulder 30 to allow the compression spring 32t0 shift the crank arm 26 to the position shown in Fig. 6, whereupon the roller 18 is free to pull the web into the housing 20 under the normal action of the rewinding spring 19.

Although but one specific embodiment of this invention is herein shown and described, it will be understood that numerous details cf the structure shown may be altered or omitted without departing from the spirit of the invention as defined by the following claims.

We claim:

l. A screen web having a spring actuated web tensioning roller at dne end of said screen, a slat at the opposite end of said web, a journal shaft extending from one end of said roller, a relatively stationary support comprising a bearing for said shaft, handle means fast on said shaft for rotating said roller manually, and latch end of said web, a journal shaft extending from one end of said roller, a relatively stationary support comprising a bearing for said shaft, handle means fast on said shaft for rotating said roller manually, coacting latch mernbers respectively on said handle means and said stationary support to lock said roller against rotation due to tension of said web, and a spring normally urgihg said members out cf such lock1n g relatron:

3. In a picture screen cornpris1ng a screeri web, having a roller at one end including a rewindingspring acting on said roller and a slat at the free end'of said web, a spring suspension for said slat having greater web pulling strength than that of said rewinding spring, a journal shaft at one end of said roller, a relatively stationary support for said shaft, handle r'neans fast 'on said shaft for rotating said roller manually, axially shiftable latch means on said shaft acting between said roller and stationary support uponybeing shifte':d manually into holding engagement with said Support for preventing rotation of said roller, and a spring. normally urging said latch means out of such holding engagernent, said latch means being held in such holding ehgagernent by the pull on said web exerted by said spring suspension when said roller has been rotated manually by said handle means to increa'se the pull on said web beyo'nd that exerted by the rewinding spring and said latch means has been shifted manually into holding engagement with said support.

4. In a picture screen, a screen web having a roller atone end thereof including a rewinding spring normally adapted t rotate said roller to Wind the web thereon, a slat at the other end, a casing in which said roller is journalled, a standard having-means for supporting said casing and slat in spaced relation to each oth er with said webextended between them, and a sus pension spring for connecting said slat'to said standard and having greater web pulling strength than that of 4 the rewinding spring, a shaft fixed 011 one end of said roller, handle means fast on said shaftfor rotating said roller manually, a latch arrnrotatable With said shaft and slidable axially thereon, an annular series cf keeper shoulders stationarily located on said casing in position for roller holding coaction with said latch arm when in one position on said shaft, a spring normally urging said latch arm along said shaft and away from such holding Position, said latch arm and keeper shoulders being held in such holding engagementby the pull on said web exerted by said spring suspension when said roller has been rotated manually by said handle means to increase the pull on said web beyond that exerted by the rewinding spring, and said latch arm is in holding coaction in one of said keeper shoulders.

5. In a picture screen, a screen web having a roller at one end thereof including a rewinding spring nor- .mally adapted 10 rotate said roller to Wind the web thereon, a slat at the other end, a casing in which said roller is journalled, a standard having means for supporting said casing and slat in spaced relation to each other with said web extended between them, and a suspension spring for connecting said slat to said standard and having greater web pulling strength than that of said. rewinding spring, a shaft fixed on one end of said roller, a bearing spider for said shaft fixed in said casing and having thereon an annular series of keeper shoulders concentric. with said=shaft, a handle disc fast on said shaft for manually applying to said web a stress in excess of that irnparted to it by the rewinding spring, a latch arm shiftable on said shaft be'tween said spider and handle disc and shiftable into and out of engagement withsaid keepershoulders, said latch arm being held in such holdingengagement by the pull on said web exerted by said spring suspension when said roller has been rotated manually by said handle means to increase the pull on said web beyond that exerted by the rewinding spring and said latch arm is in holding coaction in one of said keeper shoulders, and a helical compression spring on said shaft normally urging said arm out of shoulder eng'aging 'position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 737,769 Preston Sept. 1, 1903 1016493 I-Iaekney; Feb. 6, 1912 1097957 Whitmore May 26 1914 2,434071 Heck Jan. 6, 1948 

